Door

ABSTRACT

The present invention relates to a door capable of preventing the door from being warped or bent and also from being damaged due to the penetration of moisture. The door of the present invention comprises front and rear panels which define front and rear surfaces of the door, respectively; a pair of horizontal frames which are fixed to upper and lower ends of the front and rear panels between the front and rear panels, respectively; and a pair of vertical frames which are fixed to right and left ends of the front and rear panels between the front and rear panels, respectively. Each of the vertical frames includes an inner frame which is fixed to an innermost position and made of wood, a middle frame which is fixed to an outer side of the inner frame and made of metal, and an outer frame which is fixed to an outer side of the middle frame and made of a synthetic resin. Further, a foaming agent is filled in an inner space formed between the front and rear panels by the frames to form a foam layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a door, and more particularly to a doorconfigured so that deformation due to an external force can be avoidedby forming frames of a synthetic resin, wood and metal materials andthen forming a foam layer between the frames.

2. Description of the Related Art

A currently mass-produced door generally uses a synthetic resin to formits frame. However, in a case where the frame is made of only asynthetic resin, there is a problem in that the door is warped as awhole. For example, in a region where temperature difference betweeninside and outside of a door is great, the door is warped to give a badinfluence on the product reliability.

To compensate for the bad effect, a door frame may be made of asynthetic resin and reinforced wood. However, if it is used for a longtime, the frame may be damaged due to moisture penetrated into a woodportion thereof. For example, if paint or coating agent on the doorsurface is striped off due to long-time use, external moisture ispenetrated into the wood. Thus, there is a problem in that itsubstantially gives a bad influence on life and reliability of the dooritself.

In addition, although the reinforced wood is also used, there islimitation in strength reinforcement of the door itself. That is, sincewood has limited strength, it is not satisfactory enough to prevent thewood from being warped due to an external force as described above.

SUMMARY OF THE INVENTION

The present invention is conceived to solve the aforementioned problemsin the prior art. Accordingly, an object of the present invention is toprovide a door having relatively improved strength.

Another object of the present invention is to provide a door withexcellent heat insulation effects.

A further object of the present invention is to provide a door withminimized moisture penetration from the outside.

According to an aspect of the present invention for achieving theobjects, there is provided a door comprising: front and rear panelsdefining, respectively, front and rear surfaces of the door; a pair ofhorizontal frames fixed, respectively, to upper and lower ends of thefront and rear panels between the front and rear panels; and a pair ofvertical frames fixed, respectively, to right and left ends of the frontand rear panels between the front and rear panels, wherein each of thevertical frames comprises an inner frame which is fixed to an innermostposition and made of wood, a middle frame which is fixed to an outerside of the inner frame and made of metal, and an outer frame which isfixed to an outer side of the middle frame and made of a syntheticresin, and wherein a foaming agent is filled in an inner space formedbetween the front and rear panels by the frames to form a foam layer.

Preferably, the front and rear panels are made of either a syntheticresin or glass fiber.

More preferably, the middle frame is made of aluminum.

More preferably, the middle frame is formed to have an I-shaped sectionor the middle frame is formed to have a C-shaped section.

More preferably, the horizontal frame is made of a synthetic resin.

More preferably, upper and lower ends of the vertical frames areinstalled between the pair of the horizontal frames.

More preferably, the inner frame of the vertical frame is made of an LVL(Laminated Veneer Lumber) in which a plurality of sheets of plywood arelaminated and attached one above another, and the plurality of sheets ofplywood are attached in a right and left direction.

More preferably, grooves are formed on front and rear ends of the middleframe, respectively, in a longitudinal direction thereof; andprotrusions are formed on the front and rear panels, respectively, to befitted into the grooves.

According to the present invention so configured, there are advantagesin that the door may be prevented from being warped or bent in a foreand aft direction due to an external force caused by temperaturedifference between the inside and outside of the door and also frombeing damaged due to the penetration of moisture. Further, since theheat insulation in the building can be maximized, energy saving effectscan also be expected.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become apparent from the following description ofpreferred embodiments given in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an exploded perspective view showing a door according to thepresent invention;

FIG. 2 is a sectional view showing an end of the door according to thepresent invention;

FIG. 3 is a sectional view showing an end of the door according toanother embodiment of the present invention; and

FIG. 4 is a sectional view showing an end of the door according to afurther embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, the present invention will be described in more detail withreference to the accompanying drawings As shown in FIG. 1, a door of thepresent invention includes front and rear panels 10 and 20 that defineits front and rear surfaces, respectively. The front and rear panels 10and 20 may be made of a synthetic resin and are formed to be relativelythin. The front and rear panels 10 and 20 may be made of any kinds ofsynthetic resins only if they can define a surface while havingpredetermined strength as well as preventing moisture from beingpenetrated.

Further, it is most preferred that the front and rear panels 10 and 20be formed by hot pressing a glass fiber in consideration of theirstrength. However, the front and rear panels 10 and 20 are notnecessarily limited to the glass fiber in view of their materials, butthey may be made of any kinds of synthetic resins or glassfiber-reinforced synthetic resins. The front and rear panels 10 and 20have the substantially same shape as each other and have any shapes orpatterns on their surfaces.

Along edges between the front and rear panels 10 and 20 are installed apair of horizontal frames 30 a and 30 b and a pair of vertical frames 50a and 50 b. A pair of the horizontal frames 30 a and 30 b arehorizontally installed at upper and lower ends of the front and rearpanels 10 and 20, and substantially define the upper and lower ends ofthe door, respectively. Further, the horizontal frames 30 a and 30 b maybe made of a synthetic resin, preferably of a synthetic resin withsufficient strength, if possible. The horizontal frames 30 a and 30 bhave the same entire horizontal length as that of the front and rearpanels 10 and 20.

In addition, in a case where the horizontal frames 30 a and 30 b aremade of a synthetic resin, the frames may have strong resistance againstmoisture penetration. However, the horizontal frames 30 a and 30 b mayalso be made of reinforced wood, similarly to the vertical frames asdescribed later.

The vertical frames 50 a and 50 b of this invention define right andleft frames of the door. The vertical frames 50 a and 50 b definevertical edges at both lateral sides of the door in a state where theyare interposed between the horizontal frames 30 a and 30 b. That is,upper and lower ends of the vertical frames 50 a and 50 b are preferablysupported on the horizontal frames 30 a and 30 b in a state where theyare brought into contact with a bottom surface on right and left sideends of the upper horizontal frame 30 b and a top surface on right andleft side ends of the lower horizontal frame 30 a. According to thisconfiguration, an inner frame 52 of the vertical frame 50 a or 50 b,which is made of wood, is covered with the horizontal frames 30 a and 30b such that a wood portion of the door cannot be exposed to the outside.Therefore, the present invention has an advantage in that the door hasstrong resistance to the penetration of moisture.

A pair of the vertical frames 50 a and 50 b of the present invention areinstalled at the right and left positions sides of the door and have thesubstantially same shape as each other. Therefore, the followingdescription will be given only on the basis of the vertical frame 50 athat is positioned right as viewed from the figure.

The vertical frame 50 a of the present invention includes an inner frame52 that is installed at an innermost position and made of wood, a middleframe 54 that is brought into contact with the external side of theinner frame 52 and made of metal, and an outer frame 56 that isinstalled to the external side of the middle frame 54, i.e. theoutermost position.

The inner frame 52 is preferably formed of wood with such strength thatthe complete door cannot be warped due to an external force. To thisend, the inner frame 52 is preferably made of wood having sufficientstrength in a front and aft direction to prevent the door from beingdeformed in the fore and aft direction (i.e., toward or away from theinside of door) in a state where the door is standing upright. Forexample, an LVL (Laminated Veneer Lumber) in which a plurality of sheetsof plywood are laminated and attached one above another is preferablyused as the inner frame 52. As shown in FIGS. 1 to 3, this LVL isinstalled to provide significant structural strength against the foreand aft bending of the door since the plurality of sheets of plywood arelaminated and attached one after another in a lateral direction (i.e.,in a right and left direction) of the door.

In addition, the middle frame 54 is formed of a metal material toprovide sufficient structural strength against the fore and aft bendingof the door. The middle frame 54 can be generally made of a metalmaterial with excellent strength. The middle frame 54 may be shaped as aflat pate as shown in FIG. 1 or formed to have an I-shaped or C-shapedsection as shown in FIGS. 2 and 3. More preferably, the middle frame 54is made of aluminum among the metals, in consideration of lightweightcharacteristics, structural strength, improved forming quality and thelike.

The outer frame 56 is preferably made of a synthetic resin to completelyprevent moisture from being penetrated into the door from the outside.Further, it is apparent that the outer frame 56 may also be made of asynthetic resin containing wood powder or other additives. The outerframe 56 may be mainly made of a material capable of preventing moisturefrom being penetrated therein, i.e. a synthetic resin, but may beadditionally made of other materials in consideration of strength andsurface texture thereof.

A term “synthetic resin material” as used herein means including both amaterial composed of synthetic resin only and a material containingsynthetic resin as a main component and other additives such as woodpowder as described above.

As explained above, the vertical frame 50 a is composed of the innerframe 52, the middle frame 54 and the outer frame 56. The inner frame52, the middle frame 54 and the outer frame 56 are attached to oneanother by means of an adhesive to be formed into a complete verticalframe 50 a or 50 b as a whole.

FIG. 2 is a sectional view of an end portion of the assembled dooraccording to the present invention. As shown in this figure, it can beunderstood that the vertical frame 50 is installed at an edge betweenthe front and rear panels 10 and 20. The vertical frame 50 is composedof the inner frame 52 made of wood, the middle frame 54 made of metal,and the outer frame 56 made mainly of synthetic resin, which in turn areintegrally attached to one another by means of an adhesive.

Further, in the embodiment illustrated in FIG. 2, the middle frame 54 isformed of a metal material with an I-shaped section. The outer and innerframes 56 and 52 attached from the outside of the middle frame 54 withan I-shaped section have vertical grooves at front and rear ends thereofsuch that the outer and inner frames 56 and 52 can be completely andeasily fastened to the middle frame 54 with an I-shaped section.

Furthermore, in the embodiment illustrated in FIG. 3, it will beunderstood that the middle frame 54 made of a metal material, preferablyaluminum, is formed to have a C-shaped section, even though the otherelements are the same as those in the previous embodiment. In FIG. 3,the elements other than the middle frame are the same as those as in theembodiment shown in FIG. 2 and are designated by the same referencenumerals, respectively.

In addition, FIG. 4 is a sectional view of an end portion of theassembled door according to another embodiment of the present invention.As shown in this figure, the middle frame 54 of this embodiment hasgrooves 54 a at front and rear ends in a vertical direction, such thatprotrusions 10 a and 20 a formed on the front and rear panels 10 and 20can be fitted into the grooves 54 a. The grooves 54 a are formedvertically along the front and rear ends of the middle frame, and theprotrusions 10 a and 20 a are also formed to extend in the verticaldirection. Since the protrusions 10 a and 20 a are inserted into thegrooves 54 a on the front and rear ends of the middle frame 54,respectively, it is substantially ensured that the door can beconveniently assembled and the assembled door can be firmly preventedfrom being deformed. In this embodiment, the elements other than themiddle frame 54 are the same as those in the previous embodiment.

As described above, if the middle frame 54 is made of a metal materialand also formed to have an I-shaped or C-shaped section or with thegrooves at front and rear end thereof, it can be substantially easilyfastened to the inner or outer frame from the lateral sides thereof.Further, since a sufficient contact area is ensured, the frames can bemore easily integrated. Furthermore, if the middle frame 54 is made ofthe metal material and also has an I-shaped or C-shaped section, it canprovide greater structural strength against the fore and aft rearwardbending of the door.

As described above, if the pair of horizontal frames 30 a and 30 b andthe pair of vertical frames 50 a and 50 b are assembled at the edgesbetween the front and rear panels 10 and 20, the assembled frames havean empty space at the center thereof. In such an empty space, a foamingagent is filled to form a foam layer. The foam layer can serve toreinforce the strength of door and provide better heat insulationproperty. In FIGS. 2 and 3, a foam layer 60 is shown as being formed inthe door. Further, to form such a foam layer 60, a foaming agent shouldbe injected into the empty space in a state where the frame assembly ispositioned in an additional mold while the foaming agent is filled intothe empty space of the door such that the front and rear panels and therespective frames can sufficiently withstand a foaming pressure.

In addition, if the foaming agent is filled into the door to completelyform the foam layer 60 as mentioned above, the door can be completelymanufactured by finishing the exterior of the door. This finishingprocess may include the steps of cutting upper and lower ends of thedoor at accurate sizes and spraying a predetermined stain on the doorsurface for the surface treatment.

After the stain is sprayed on the door surface, the surface on which thestain has been sprayed may be polished with a soft fabric and the liketo further provide a three-dimensional effect to a design or patternformed on the front and rear panels 10 and 20. This polishing workallows the stain to be uniformly distributed at uneven portions of thepanels, thereby sufficiently expressing the three-dimensional effect.Further, after the stain has been sprayed and dried, a predeterminedcoating agent is sprayed on both surfaces of the door to complete thedoor.

The door of the present invention so configured has sufficientstructural strength by means of the middle frame 54 made of metal (e.g.,aluminum) in addition to the inner frame 52 made of wood. In particular,the middle frame 54 can provide structural strength enough to preventthe door from being warped frequently at regions where the temperaturedifference between the inside and outside of a room is extremely large.

In addition, since the outer frame 56 is made mainly of a syntheticresin capable of preventing moisture from being penetrating into thedoor, it is possible to prevent the moisture penetration, and thus, thedamage of door.

According to the present invention described above, the followingadvantages can be expected.

First, since the vertical frame of the door is provided with the middleframe made of metal (e.g., aluminum), there is an advantage in that thedoor is very strong against the fore and aft bending thereof. Therefore,since the door can sufficiently withstand an external force caused bythe large temperature difference between the inside and outside of aroom or an unexpected external force applied from the inside and outsideof the door, it is possible to prevent damage of the door such asbending or warping, and thus, to further improve the productreliability.

In addition, the prevention of damage such as the bending or warping ofthe door means that a gap is not substantially generated between theframes, and thus, the heat insulation effect can be maximized.Therefore, it can be further understood that the door of the presentinvention is very useful in view of energy saving effect.

Furthermore, since the outer frame and the horizontal frame are mademainly of a synthetic resin and these frames also define the entireexterior of the door, there is an advantage in that the door issufficiently strong against the moisture penetration.

It will be apparent that those skilled in the art can make variousmodifications and changes within the scope of the fundamental technicalspirit of the present invention. Accordingly, the scope of the presentinvention should be construed on the basis of the appended claims.

1. A door, comprising: front and rear panels defining, respectively,front and rear surfaces of the door; a pair of horizontal frames fixed,respectively, to upper and lower ends of the front and rear panelsbetween the front and rear panels; and a pair of vertical frames fixed,respectively, to right and left ends of the front and rear panelsbetween the front and rear panels, wherein each of the vertical framescomprises an inner frame which is fixed to an innermost position andmade of wood, a middle frame which is fixed to an outer side of theinner frame and made of metal, and an outer frame which is fixed to anouter side of the middle frame and made of a synthetic resin, andwherein a foaming agent is filled in an inner space formed between thefront and rear panels by the frames to form a foam layer.
 2. The door asclaimed in claim 1, wherein the front and rear panels are made of eithera synthetic resin or glass fiber.
 3. The door as claimed in claim 1,wherein the middle frame is made of aluminum.
 4. The door as claimed inclaim 1, wherein the middle frame is formed to have an I-shaped section.5. The door as claimed in claim 1, wherein the middle frame is formed tohave a C-shaped section.
 6. The door as claimed in claim 1, wherein thehorizontal frame is made of a synthetic resin.
 7. The door as claimed inclaim 1, wherein upper and lower ends of the vertical frames areinstalled between the pair of the horizontal frames.
 8. The door asclaimed in claim 1, wherein the inner frame of the vertical frame ismade of an LVL (Laminated Veneer Lumber) in which a plurality of sheetsof plywood are laminated and attached one above another, and theplurality of sheets of plywood are attached in a right and leftdirection.
 9. The door as claimed in claim 1, wherein grooves are formedon front and rear ends of the middle frame, respectively, in alongitudinal direction thereof; and protrusions are formed on the frontand rear panels, respectively, to be fitted into the grooves.